In 1982, a retired British probation officer named David Martin was cleaning the chimney of his home in Bletchingley, about 20 miles south of London, during a renovation when he discovered the remains of a pigeon among the debris. But while he was pulling out the bird’s dessicated corpse, he made a surprising discovery. As Martin told the BBC, he realized he had no ordinary bird on his hands when “down came the leg with the red capsule on with a message inside.”

The red capsule contained a handwritten message, written in code, with the words “Pigeon Service” at the top — indicating the bird assisted Allied Forces during World War II. But in 1982, British code-breakers had other priorities, the New York Times reported — namely, the ongoing Falklands War, a 74-day conflict between Britain and Argentina over ownership of the Falkland Islands in the South Atlantic — which pushed Martin’s pigeon and its mysterious message to the bottom of their to-do list.

But Martin’s story attracted attention from pigeon enthusiasts, who began a campaign that ultimately persuaded Britain’s Government Communications Headquarters to give the code a second look. Last week the GCHQ released a statement about the message, but the organization’s limited findings have ruffled some feathers.

GCHQ analysts believe the code in the pigeon’s capsule was created using a one-time pad — a method of encryption that is difficult to crack without knowing the key. “Unfortunately, much of the vital information that would indicate the context of the message is missing,” the GCHQ release stated. “This means that without access to the relevant codebooks and details of any additional encryption used, it will remain impossible to decrypt.”

Among the details that GCHQ were able to decrypt were the note’s sender, “Sjt. W Swot,” and its code-named recipient, “xo2″ — believed to be British Bomber Command, according to the Times. But the location of Martin’s residence — just five miles east of the headquarters of Field Marshal Bernard Law Montgomery, commander of Allied ground forces during D-Day, and squarely between the Normandy beaches and the famous code-breaking center of Bletchley Park, which also reportedly held a MI6 pigeon loft — has Martin and others suspicious that they’re not being given the whole story.

“I think there’s something about that message that is either sensitive or does not reflect well on British special forces operating behind enemy lines in wartime France,” Martin told the Times. “I’m convinced that it’s an important message and a secret message.”

GCHQ analysts, however, remained nonplussed. “We didn’t really hold out any hopes we would be able to read the message,” said Tony, a GCHQ historian who asked to be identified by first name only, to the BBC. “Unless you get rather more idea than we have of who actually sent this message and who it was sent to we are not going to find out what the underlying code being used was.”

Tony told the BBC the code will remain a mystery unless members of the public come forward with information that could help identify the sender.

“There are still quite a lot of people alive who worked in communications centers during the war and who might have some knowledge about this,” he said. “It would be very interesting if anyone did have information if they could put it in the pot and we could see if we could get any further with it.”